High-performance, high-speed and compact electronic systems are seeing increasing demand as the electronic industry matures. Various semiconductor package techniques have been proposed to meet such a demand. For example, a semiconductor package device may be configured to include a plurality of semiconductor chips mounted on a package substrate or to have a package-on-package (PoP) structure. Since each package of the PoP device has a semiconductor chip and a package substrate, the PoP device has a large thickness causing various technical problems. In addition, for the PoP device, it is difficult to exhaust heat generated in semiconductor chips to the outside, and thus, the PoP device suffers from technical problems, such as a device malfunction or a reduction in operation speed.